Scientists Reveal Secrets of the Blarney Stone
Geologists at the University of Glasgow’s Hunterian Museum have discovered a
possibly unique 19th century microscope slide, cut from the famous Blarney Stone, at
Blarney Castle, near Cork in Ireland.
The Blarney Stone, said to bestow the gift of eloquence on those who kiss it, is
steeped in rumour and myth, and there seems to be little published evidence of its
true nature.
There are a wide range of legends about the origins of the stone. Wikipedia claims
that it is a “bluestone” like those at Stonehenge. Elsewhere it’s claimed that it was
part of the true Stone of Destiny, given to Cormac MacCarthy by a grateful Robert
the Bruce following Bannockburn. Various accounts suggest associations with Moses,
King David, or with the death of St Columba, but there is no clear source for these
speculations.
However, others suggest that the stone is locally derived from limestone quarries
near Blarney, and you can even buy bits of limestone marketed as being the same as
the Blarney stone.
So what is it?
For the first time, the true nature of the Blarney Stone can be revealed. The historic
microscope slide, containing a slice of the Stone ground so thin that it is transparent
to light, indicates that it is a limestone made of the mineral calcite, and containing
recrystallized and slightly deformed fragments of fossil brachiopod shells and
bryozoans. This strongly supports views that the stone is made of local
Carboniferous Limestone, about 330 million years old, and indicates that it has
nothing to do with the Stonehenge bluestones, or the sandstone of the current
“Stone of Destiny”, now in Edinburgh Castle.
The rediscovery of the microscope slide
The Hunterian has around 40000 geological microscope slides, and the older ones
are mostly catalogued in hand-written ledgers. The Blarney Stone slide had escaped
notice until now, but it was spotted in the catalogues during a digitisation
programme being carried out by Becky Smith, a Museums Galleries Scotland funded
collections intern, and then swiftly located in our well-organised collections.
The slide is part of the rock and mineral thin-section collection put together by
Professor Matthew Forster Heddle, of St. Andrews, one of the giants of 19th century
geology and chemistry in the UK. It was probably made between 1850 and 1880,
during the period when new microscope techniques began to revolutionise our
understanding of rocks, and how they form. He was a pioneer in the use of these
techniques to investigate the rocks and minerals of Scotland, and elsewhere. He also
seems to have managed to obtain fragments of a number of important historical
stones: the collection also includes slides cut from several of the stones at
Stonehenge. This was not vandalism – it was bringing the latest scientific tools to
bear on the origins of these monuments.
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We don’t know how Professor Heddle got the Blarney microscope slide, or whether
he had it made himself, but he was a major scientific figure, with excellent contacts,
and was always keen to acquire interesting samples for scientific investigation.
However, in this case, he doesn’t seem to have published anything about the stone.
During the mid-19th century, the castle was an uninhabited semi-ruin, but visiting the
stone was popular, and Heddle or some other geologist or antiquarian must have
collected a sample. At that time, the Stone could only be accessed by hanging upside
down from the battlements, so using a hammer to sample the Stone would have
been a difficult acrobatic feat. Perhaps they bit a piece off instead of kissing it!
Very few pieces of the Blarney Stone seem to exist outside Blarney Castle. Apart
from our microscope slide, the only other one I’m aware of is in a monument at the
University of Texas. However, this object seems to have its origins in a beer-fuelled
party, and the genuineness of the fragment must be in doubt.
The Blarney Stone is famous for bestowing the gift of eloquence on those who kiss
it. We don’t know if kissing the microscope slide would have the same effect,
although Dr Faithfull has tried it.
For more information, please contact Becky Smith (Rebecca.smith.2@glasgow.ac.uk)
or Dr John Faithfull (john.faithfull@glasgow.ac.uk) on 0141 330 4213
Images
Images can be downloaded at: http://www.hmag.gla.ac.uk/john/blarney
The width of the field of view is about 1.7mm on each of the microscope images.
The Blarney Stone is practically all made of one mineral – calcite, but some of this
calcite is from fossil shell and skeletal material, and some has crystallized later,
cementing the fossil fragments together.
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